What is the value of the following logarithm? $\log_{81} 9$
Explanation: If $b^y = x$ , then $\log_{b} x = y$ Notice that $9$ is the square root of $81$ That is, $\sqrt{81} = 81^{1/2} = 9$ Thus, $\log_{81} 9 = \dfrac{1}{2}$.